The research plan is a continuation of our current work which correlates the asymmetric distribution of pyrimidine-rich clusters and oligothymidylate tracts in strands L and H of Bacillus subtilis DNA with their in vivo transcribing function during morphogenesis (germination and sporulation), and their function during genetic recombination (transformation). The experimental approach involves the following: 1) Hybridization behavior with respect to strand selection of mRNA species made at consecutive stages of spore outgrowth, the first cycle of synchronous growth and during spore formation. 2) Physical isolation of L-specific and H-specific mRNA hybrids after hybridization-competition experiments followed by sequence analysis) and its transcription product (fingerprint patterns after nuclease digestions). 3) Fate of individually labeled L and H in heteroduplex molecules in recipient B. subtilis cells. and 4) Determinations of cotransfer frequencies, linkage characteristics and mutagenesis in recipient B. subtilis cells transformed with a) heteroduplex molecules carrying linked traits in the trans configuration and b) with purified natural and chemically induced cross-linked DNAs. These studies will elucidate whether correction mechanisms are asymmetric, are they likely to induce mutagenesis and is there strand preference during integration of donor DNA in B. subtilis. BIBLIOGRAPHIC REFERENCE: Testa, D. and Rudner, R. Medium-induced asporogenous phenocopies of Bacillus subtilis DNA. Fed. Proc. 35, 1584 (l976).